Aeroplane fabric and process of coating the same



methyl acetate or acetone formin permeabilizing and stretching liquid,to

strength and rigidity,

Patented June 29, 1926.

UNI-TED STATES PATENT: OFFICE;

THEODORE F. TESSE, OF PARIS, FRAIV CE.

v AEROPLANE FABRIC AN D PROCESS OF COATING THE SAME.

Application filed December 12, 1922. Serial No. 606,493.

In my copending applications, Serial Nos. 71,201 and 123,640, the latternow being Patent 1,521,055 granted Dec. 30, 1924, I have described a newprocess of coating aeroplane fabrics consisting essentially inimprisoning between two stretching layers of coating material, anintermediate layer (or a plurality of intermediate layers) of coating,

material whichis very supple and plastic and compounded from (ascharacteristic ingredients) the following five materials 1. A dilutesolution of cellulose acetate in an imwhich are added as dilutives',alcohol and benzol.

2. A liquid having a higher boiling point than the solvent or dilutiveswhose function is to prevent precipitation of the cellulose ester duringevaporation of the volatile solvent, as, for example, benzyl alcohol oraceto-acetic ether.

.pleness and softness, such as triacetin.

4. A liquid actin' as a plasticifying agent to increase the asticity,and having a boiling point higher than 200 0., for example eugenol.

5. An inert solid substance which apart from giving colorormetallization effects, imparts some stretching power "and gives whichsubstance may be a pigment, or a very finely divided metal, flake,metal, or a plurality of such.

These several layers as referred to, form.

a homogeneous covering having elasticity and suppleness and at the sametime, the

' necessary rigidity and strength.

The said process produces an improved coating, which, so far as I amaware, is-

superior to any previously advanced, but it has been found in practicethat in many instances, es eciall in cases where the plane is to be sujecte to severe changes in temperature and hygrometric degree, it isbetter to modify the differences between the compositions of theadjacent layers of the composite coating, or in other words, an;advantage is obtained when the outer or rigid layers of the math aremore closely coordinated with the mtermediate layer.

I have therefore found it to be advisable to add to the compositionsused for forming the two outer layers of the coating, particularly whenthe coating is to be subjected to a wide range of temperature variationand a wide hygrometric range, a certain amount of high boiling pointliquid. The amount used, however, must always be much less than theamount used in the, intermediate layer.

In the drawing forming apart of this application, there is shown asection of each layer of the fabric, the material employed beingdescribed on the drawing.

In order to illustrate the invention, the relation between the amount ofplasticifying or softening agents in the intermediate layer and theamount in the exterior layer ma be expressed by the ratio of 6 to 2,althoug this ratio does not have to be, followed exactly, the actualratio being subject to some degree of variation.

In addition to the use of a softening or filasticlfying agent in theexterior layers, it

as also been found advisable to use in these layers a certain amount ofa liquid such as benzyl alcohol or aceto-acetic ether whose function isto avoid too rapid an evapora- (linen being preferred). being alreadyat- U tached to the skeleton of the planes, is first coated, as in myprior applications, with an impermeabilizing and stretching liquid,which is allowed to dry (i. e. the solvent allowed to eva orate) therebyforming what I refer to as layer I.

Then one or moe layers of the second composition as above described, isor are applied, and allowed to dry, forming what I refer to as layer II.

Finally a third coating of composition similar to that used inv thefirst coating layer is applied, and allowed to dry. forming what I referto as layer III. practice I find it usually advantageous to employ thesame coating compositions for layers I and III, while layer II is of a.different. composition.

Without limitingthe invention to the detailsthereof, and merely for thepurpose of more fully 'llustrating'the invention, I give the followingillustrative example of com- .positions which may be employed in the beproduced thereby.

plying a composition made of a solution of cellulose acetatecontaining'S to 10 parts of cellulose acetate in to 70 parts of methylacetate or acetone together with 20 parts of approximatel equal volumesof alcohol and benzol tow ich is added about 2 .parts of benzyl alcoholand about 1 part of triacetin.

Layer II can be formed by applying one or more coats of a compositionmade up of a solution ofcellulose acetate containing 7 to 8 parts ofcellulose acetate in 60 to parts of methyl acetate or acetonet0getherwith 22 parts of ap roximately equalare not claimed herein, butwhich are includedlin the claimed my Patent 1,521,056 granted-Dec. 30,1924) I may substitute various equivalents, as described in my copendingapplication referred to.

The alcohol-benzene mixture is used as a dilutive. The t riacetineimparts a certain degree of softness, suppleness and flexibllity to thecoating. The benzyl alcohol prevents too rap d evaportion of thevolatile solvent, and thereby prevents precipitatlon of the celluloseester which would be in: dicated by the production of white spots of abrittle and fragile nature, in the coatingl).

In t e intermediate layer or layers, the eugenol or isoeu 1101 im artsthe necessary degree of; lastlcity an elasticlty to the coating. e inertmaterial serves to oyercome any excessive softness of the coatmg, andthe slackness 'of thecloth which may other words, 1t restores thestrenand to a; certain exte'iit,'j thefirigidity of the coating. Thisinert'material 'may'also serve as a,pig'ment to produce thedeSlI'GdfiOlOI ofthe plane. The aluminum flake, also serves to astilllarger extent to strengthen the coating, to impart the necessaryrigidity, and both the mert material and the flake-form metal serve to alarge extent, to prevent sunlight from penetrating into the coating,whereby the coating is made more resistant and stable. Both of thesematerials also decrease the flammability of the coating, and of thefabricor cloth coated.

It will be seen. that the present invention is an improvement upon thatdescribed in my Patent 1,521,055, an important difference beingthatithe-layers I and III contain an agent ca ableof preventing theprecipitation of t e celluloseester', and also contain a relativelysmallampunt of an agent for im artin I suppleness' and flexibilitythereto. The ad dition'of the triacetine in the lay- I said intermediatelayer.

ers I and III is found to be a. distinct advantage also, since there isproduced a better bonding or a more perfect union between the successivelayers of the coating, this condition being produced by making thesesuccessive layers more analogous to each other than in my Patent1,521,055.

While I have referred especially to cellulose acetate as the base of thethree layers of the coating, it is obvious that-I may employ celluloseesters of other fatty acids, e. g. formate, propionate, etc. I do notemploy the nitrate, since (aside from differences in strength, chemicalstability, etc.) the nitrate is entirely too readily inflam- 'mahle tobe used for the purpose.

The flake form of aluminum may be pre pared by passing arather coarsealuminum powder between rolls under heavy pressure. While other metals'may be used in place of this, aluminum is to be given the preference.The flake form of the. aluminum or other metal strengthens the coatingmuch more than a fine impalpable powder. These flakes overla ping eachotherto some extent, form a rigi elastic web, cemented together by thecellulose ester composition, which adds materially to the strength ofthe coatlayers containing an agent capable of im-' parting plasticityand elasticity, an e ent capable of imparting sup leness and. exibility,and an agent cape le of preventing the precipitation of cellulose ester,and solid material capable of increasing the strength; theouter layerscontaining an. agent capable of preventing the precipitation ofcellulose ester, and containing an amount of a cut ca able of impartingsuppleness and exibi ity, less than the amount present in the 2. Aprocess which comprises coating fabric parts of an aeroplane, afterapplication to a frame-work, with a succession of at least three closelyadherent layers of material having a cellulose ester of a fatty acid asprimary ingredient, an intermediate of suc layers having ingredientscapable of imparting elastic ty, plasticity,.. strength, opacity andrigidity,.and a relatively large degree of flexibility and supplness,the

pable of preventing the precipitation of the a succession of at leastthree layers of compositions each having a fatty acid ester of celluloseas a base, an intermediate one of which layers, has a greaterelasticity, and flexibility than the other layers, and which contains asolid inert material, and a metal in the form of thin flakes.

4. A fabric forming the covering of an aeroplane, said fabric beingprovided with a composite coating comprising a succession of at leastthree layers of compositions each having a fatty acid ester of celluloseas a base, an intermediate one of which layers has a greater elasticityand flexibility than the other layers'and which contains a metal 7 inthe form of thin flakes.

5.-A fabric forming the covering of an aeroplane, said fabric beingprovided with a composite coating comprising a succession of at leastthree layers of compositions each having a fatty acid ester of celluloseas a base, has the outer layers; and the outer layers containing anagent capable of preventing the precipitation of cellulose ester duringthe evaporation of the volatile solvent, together with an agent capableof imparting suppleness and fiexibilitydess than the amount present inthe said intermediate layer.

6. A tough film coating carried on a base, such coating carryingembedded therein, a multiplicity of small extremely thin metallic flakesoverlapping each other, whereby such coating is strengthened andreinforced without losing its flexibility,

In testimony whereof, I have hereunto set my hand this 27th day ofOctober, 1922.

THEODORE F. TESSE.

an intermediate one of which layers a greater elasticity and flexibilitythan

